Abstract Language and communication deficits are one of the hallmarks of autism spectrum disorders (ASD). Language delay is often the first concern of parents, and early language abilities are predictive of broader outcomes for children on the autism spectrum. Recent studies have noted that comprehension is relatively more affected than production in young children with ASD, yet little research has focused on this aspect of early language functioning. Contemporary versions of the weak central coherence account suggest that autism is characterized by a cognitive style in which there is a bias towards local or low-level perceptual processing rather than global, integrative processing. This theoretical account yields specific hypotheses regarding early phonological and semantic processing which will be tested in this project. The proposed research will employ implicit eye-gaze paradigms developed to assess real-time comprehension (lexical representations) in typically developing infants and toddlers. A series of five studies are planned to address the following three specific aims: 1) to investigate the hypothesis that toddlers with ASD display a bias towards enhanced perceptual processing in lexical tasks compared to typically developing peers; 2) to examine the claim that toddlers with ASD exhibit poorer contextual integration on lexical tasks than typical controls; and 3) to determine whether early phonological and semantic processing abilities predict later language outcomes. A total of 150 toddlers will participate, 75 with ASD and 75 typically developing toddlers matched on parent-reported vocabulary comprehension and sex. A looking-while-listening paradigm will be used in Studies 1-4. Study 5 will involve a 1-year follow-up assessment to examine predictors of language outcomes as well as re-administration of one of the comprehension processing tasks. This research is significant in that it will provide a comprehensive characterization of early lexical processing in toddlers with ASD and provide the first systematic evaluation of whether the weak central coherence account can help explain the early comprehension deficits in this group. Findings will lead to better understanding of the autism phenotype(s) and have direct implications for developing early interventions.